NetWorker: NMC Server database Backup Failing With "no matching devices for save of client"

74920:save: Step (4 of 6) for PID-10128: Contacting the NetWorker server through the nsrd process to obtain a handle to the target media device through the nsrmmd process for the save set '/nsr/nmc/nmcdb_stage/pgdata'.
174908:save: Saving the backup data in the pool 'backup_pool'.
175297:save: Unable to set up the direct save with server 'networker_server': no matching devices for save of client `nmc_server'; check storage nodes, devices or pools.

The error indicates that it is detecting no matching devices for save of client NMC_Server. 

The NMC Server backup workflow defines the pool used for backup; however, the default override option is "Client can override"
 

The NMC server's client resource has a different pool defined.

The pool listed in the client resource is not mounted or misconfigured.

The error 'Check storage nodes, devices, and pools' is general and may appear for other reasons. If the NMC server client properties lack a pool setting and this failure occurs, see the Additional Info section for troubleshooting steps.

Remove the pool specification from the NMC server's client resource:
 

The pool specified in the backup action is used instead.

NetWorker: Troubleshooting Media Waiting Events - waiting for 1 writable volume or no matching devices